The method for determining risk of metastatic relapse in a patient diagnosed with colorectal cancer (CRC) can include detecting a level of at least one indicator of metastatic potential in a biological sample from the patient, comparing the level of the indicator of metastatic potential with a control, and identifying the patient as one who is at risk of metastatic relapse and a candidate for chemotherapy if an aberrant level of the indicator of metastatic potential in the biological sample compared to the control is detected. The at least one indicator of metastatic potential can include at least one metastasis-inducing gene and/or at least one metastasis suppressor gene. An aberrant level of the at least one indicator of metastatic potential can include a copy number gain of the metastasis-inducing gene and/or a copy number loss of the metastasis-suppressor gene.